The Envirco ITR-9 series of electronic fan speed controllers regulate the speed of single-phase (110—240 VAC / 50—60 Hz) voltage controllable motors by varying the supplied voltage. The ITR-9 controllers provide automatic power supply detection. The minimum speed is adjusted via an internal trimmer. The output is regulated by a potentiometer in the range between the minimum output voltage and the supply voltage. The series features an unregulated output for connecting a valve, lamp, damper, etc. There are two start-up modes - kick start and soft start, selectable via a jumper.